Gels formed by the interaction of poly(aldehyde) with various substances

ABSTRACT

The present invention, which addresses the needs of the prior art, provides irreversible, hydrophilic gels which can be incorporated into dressing compositions, dermatologically compatible compositions, wound packings, wound dressings, burn dressings, drug delivery dressings, dry films, cosmetic masks and cosmetic wrap dressings. The gels of the invention include a blend of a hydrophilic poly(aldehyde) and a polymer selected from the group consisting of a poly(amide), a poly(amine) and a poly(alcohol).

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. application Ser. No.09/248,591, entitled Gels Formed By The Interactio With VariousSubstances, filed on Feb. 11, 1999 now U.S. Pat. No. 6,121,375, thedisclosure of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates to the field of stable, irreversible,hydrophilic gels and more particularly to blends of poly(amide, amine oralcohol) and hydrophilic poly(aldehyde) which can be used in dressingsfor a variety of applications including cosmetic applications.

It has been known that polyvinyl-pyrrolidone (PVP) complexes withpolyurethanes to yield hydrophilic blends which can be used as wounddressings or in cosmetic preparations. For example, U.S. Pat. No.5,156,601 discloses a dressing which includes a tacky gel ofpolyurethane and a poly(N-vinyl lactam) such as PVP with a degree ofring opened pyrrolidone groups. U.S. Pat. No. 5,420,197 describeshydrophilic gels formed by poly(N-vinyl lactams) such as PVP with adegree of ring-opened pyrrolidone groups, and chitosans. Otherreferences of general background interest include U.S. Pat. Nos.5,135,755 and 5,206,322.

Although some of the hydrophilic gels described in the art can be usedfor wound dressings and other dermatologically compatible applications,many hydrophilic gels known in the art are reversible and have atendency to cold flow. Accordingly, there is still a need in the art ofdressings, implants and dermatological compositions for gels which areirreversible and do not exhibit cold flow.

It is therefore an object of the invention to provide dressingcompositions and dermatologically-compatible compositions which includegels having hydrophilic and absorbent properties and which do notexhibit cold flow.

It is a further object to produce gels without a need for expensiveequipment and/or processing.

It is another object to provide gels of poly(aldehyde) and poly(alcohol,amine, amide) which can be used in a variety of products such as cavitydressings, drug delivery patches, face masks, implants and wounddressings.

SUMMARY OF THE INVENTION

The present invention, which addresses the needs of the prior art,provides irreversible, hydrophilic gels which can be incorporated intodressing compositions, dermatologically compatible compositions, woundpackings, wound dressings, burn dressings, drug delivery dressings, dryfilms, cosmetic masks and cosmetic wTap dressings. In one aspect of theinvention, the gels include a blend of a hydrophilic poly(aldehyde) anda polymer selected from the group consisting of a poly(amide), apoly(amine) and a poly(alcohol) and mixtures thereof.

The hydrophilic poly(aldehydes) useful in preparing the gels of thisaspect of the invention include, but are not limited to, a homopolymer,a (co)polymer or a terpolymer of acrolien, vinyl formal, glutaricdialdehyde and mixtures thereof. Poly(amides) useful in forming the gelsinclude, but are not limited to, a homopolymer, (co)polymer orterpolymer derived from acrylamide, N-vinyl lactams, N-vinyl formal andmixtures thereof. Poly(amines) useful in preparing the gels of thepresent invention include, but not limited to, a homopolymer,(co)polymer or terpolymer derived from ethylene diamine, allylamine,vinyl pyridine, N-vinyl formal, chitosan, vinyl amine and mixturesthereof. Poly(alcohols) useful in the present invention include ahomopolymer, (co)polymer or terpolymer derived from hydrolyzedpoly(vinyl acetate), allyl alcohol, ethylene glycol, ethylene oxide andmixtures thereof.

In another aspect of the invention, the gels include two components. Thefirst component includes a water-soluble (co)polymer, which ispreferably from about 1 to about 50 weight % in a solution. Thewater-soluble (co)polymer of the first component is prepared by grafting(meth)acrolin onto a (co)polymer. The second component includes a watersoluble (co)polymer, which is preferably from about 1 to about 20 weight% in a solution. The water soluble (co)polymer of the second componentis functionalized with an amino group, alcohol, acid, or mixturesthereof.

In another embodiment, the (meth)acrolien can be grafted ontopoly(ethylene oxide), poly(propylene oxide), or homopolymers or(co)polymers of ethylene glycol or N-vinyl pyrrolidone. The watersoluble (co)polymer containing amide, alcohol or acid functionalityincludes poly(ethylene imine), poly(vinylalcohol), chitosan, cellulose,poly((meth)acrylic acid)), and (co)polymers thereof. The weight ratio ofthe first component to the second component can be from about 12:1 toabout 1:1.

The gel is prepared in an aqueous solution at a total polymerconcentration of from about 5 weight % to about 50 weight %. The aqueoussolution comprises water or a mixture of water and alcohol.

In another embodiment, the hydrophilic gel includes at least oneadditional ingredient selected from the group consisting of asurfactant, a fragrance, and a biologically active material. Theadditional ingredient can be releasable from the hydrophilic gel. Theadditional ingredient can include nitroglycerin, scopolamine,pilocarpine, ergotamine tartrate, phenylpropanolamine, theophylline,tetracycline, nemoycine, oxytretracycline, triclosan, sodium cefazolin,silver sulfadiazine, salicylates, nicotinates, capsaicin, benzocane,α-hydroxy acids, vitamins, biostats or mixtures thereof.

In another embodiment, the (meth)acrolin is (co)polymerized withN-vinylpyrrolidone or N-caprolactam.

The functionalized water soluble (co)polymer can be poly(ethyleneimine), poly(vinyl alcohol), chitosan, cellulose, poly((meth)acrylicacid)) or (co)polymers thereof.

The gel is prepared in an aqueous solution at a total polymerconcentration of from about 5 weight percent to about 50 weight percent.The aqueous solution comprises water or a mixture of water and alcohol.

In another embodiment, the hydrophilic gel further includes at least onesubstrate. The substrate is selected from the group consisting ofpolymer film, polyutherane film, polyester film, poly(amino acid),collagen film, woven fabric, and non-woven fabric. The substrate can bestretchable. Examples of substrates include, but are not limited to, arelease liner and a cell culture.

Another aspect of the invention is related to a method for preparing astable, irreverisable hydrophilic gel. The method includes mixing anaqueous solution of a poly(aldehyde) or (co)polymer with an aqueoussolution of a poly(amine), poly(alcohol) or a poly(amide) in a weightratio from about 12:1 to about 1:1. The resultant solution is then cureduntil a gel is formed. The curing is preferably performed for a periodof time of from about 10 seconds to about 2 hours.

In another embodiment, the method for preparing a stable, irreverisablehydrophilic gel includes adding a biologically active material to themixture of aqueous solutions. The biologically active material can be ananti-microbial agent.

The gel can be formed into a dressing by casting two separate slabs ofsaid gel onto two substrates, applying a solution of a biologicallyactive material onto a surface of one of the slabs, and compressing theslabs together with the biologically active material located between theslabs.

The gel preferably includes at least one additional ingredient which maybe releasable from the gel. Preferably, the releasable ingredient is asurfactant, a fragrance, a biologically active material, or abioeffecting or body-treating material.

The dressing compositions of the present invention have the advantage ofself-adhesion to the skin but with facile peelability. As a result ofthe present invention, gels are provided which are stable even in hotwater, are capable of absorbing many times their weight in water, andare capable or delivering medicaments externally to the body exactlywhere desired. Most importantly, the products based on the gels of thepresent invention have the unexpected property of resisting cold flow.

Other improvements which the present invention provides over the priorart will be identified as a result of the following description whichsets forth the preferred embodiments of the present invention. Thedescription is not in any way intended to limit the scope of the presentinvention, but rather only to provide a working example of the presentpreferred embodiments. The scope of the present invention will bepointed out in the appended claims.

DETAILED DESCRIPTION

The present invention is an irreversible, hydrophilic gel used indressing compositions, wound packings, wound dressings, burn dressing,drug delivery dressings, dry films, cosmetic mask dressings and cosmeticwrap dressings. In one embodiment of the invention, the stable,irreversible, hydrophilic gel of the invention includes a two componentblend. One component is a hydrophilic poly(aldehyde) and the other is apoly(amide), poly(amine) or poly(alcohol) and mixtures thereof.

The hydrophilic poly(aldehyde) is obtained by grafting aldehyde monomersonto poly(N-vinyl lactams). Aldehyde monomers include withoutlimitations acrolien, vinyl formal and glutaric aldehyde. Thesecompounds are readily commercially available from Aldrich Chemical Co.as an example.

In its monomeric form, acrolein is very reactive and rather toxic. Whengrafted onto a long chain biocompatible polymer such as, for example,polyvinyl pyrrolidone(PVP) or polyethylene glycol (PEG), a hydrophilic,highly reactive, nontoxic, large poly(aldehyde) is obtained.

In addition to PVP, other suitable homopolymers, (co)polymers andterpolymers of N-vinyl lactams can be used in the preparation of thehydrophilic poly(aldehyde) of the present invention.

The term poly(N-vinyl lactam) as used herein shall be understood toinclude, but is not limited to, homopolymers, (co)polymers andterpolymers of N-vinyl lactams such as N-vinylpyrrolidone,N-vinylbutyrolactam, N-vinylcaprolactam, and the like, as well as theforegoing prepared with minor amounts, for example, up to about 20weight percent, of one or mixture of other vinyl monomers(co)polymerizable with the N-vinyl lactams. (co)polymers or terpolymersof poly(N-vinyl-lactam) may comprise N-vinyl-lactam monomers such asvinylpyrrolidone (co)polymerized with monomers containing a vinylfunctional group such as acrylates, hydroxyalkylacrylates,methacrylates, acrylic acid or methacrylic acid, and acryl-amides. Ofthe poly(N-vinyl lactam) homopolymers, the polyvinylpyrrolidone (PVP)homopolymers are preferred. Of the poly(N-vinyl lactam) (co)polymers,vinyl pyrrolidone, acrylamide (co)polymers are preferred. Suitablepoly(N-vinyl lactam) terpolymers, but not limited to, isvinylpyrrolidone, vinylcaprolactam, and dimethylaminoethyl methacrylate.A variety of polyvinylpyrrolidones are commercially available.

A lactam may be considered to be a cyclic amide produced from an aminoacid through the elimination of a molecule of water from the —COOH and—NH₂ groups. A lactam, therefore, contains a —NH—CO— group in a ring. AnN-vinyl lactam has a vinyl group at the ring nitrogen and the monomercan be polymerized through the vinyl group.

It has been unexpectedly found that when the large, reactive hydrophilicpoly(aldehyde) obtained by grafting monomeric aldehydes ontopoly(N-vinyl lactams) is mixed with polymers bearing alcohol, amide oramine functionalities, or when a water soluble (co)polymer prepared bygrafting (meth)acrolin onto a (co)polymer is mixed with a water-soluble(co)polymer that is functionalized with an amino group, alcohol, acid,or mixtures thereof, a hydrophilic, irreversible gel, with no leachablealdehydes is formed. As used herein, “hydrophilic” means having a strongtendency to bind or absorb water which results in swelling and formationof gels. Further, as used herein “irreversible gel” means a materialwhich does not loose its structural integrity upon heating, irradiation,or mild chemical additions such as, for example, agar, andpoly(acrylamide) gels.

It has also been surprisingly found that the hydrophilic, irreversiblegels of the present invention have the very valuable property of beingable to resist cold flow.

“Cold flow” refers to creep at room temperature. Due to its viscoelasticnature, plastic materials subjected to a load for a period of time tendto deform more than they would from the same load released immediatelyafter application. The degree of this deformation increases with theduration of the load and with rising temperature. Creep is the permanentdeformation resulting from prolonged application of a stress below theelastic limit. This deformation, after any time under stress, is partlyrecoverable (primary creep) upon the release of the load and partlyunrecoverable (secondary creep). As used herein “cold flow” refers tothe property of the irreversible gels of the present invention to looseits structure over time due to the applied force of gravity.

Polymers bearing alcohol, amide or amine functionalities refer to, butnot limited to, poly(alcohols), poly(amides) and poly(amines) alsoincluding natural poly(alcohols), poly(amides) and poly(amines).Poly(alcohols) useful in reacting with poly(aldehydes) to form thehydrophilic irreversible gels of the present invention include, but arenot limited to, commercially available hydrolyzed poly(vinyl acetate),allyl alcohol, cellulose, ethylene glycol, ethylene oxide and mixturesthereof.

Useful poly(amides) include, but are not limited, to commerciallyavailable acrylamide, N-vinyl lactams, N-vinyl formal and mixturesthereof.

Poly(amines) useful in the formation of the gels of the presentinvention include, but are not limited to, commercially availableethylene diamine, allyl amine, vinyl pyridine and chitosan.

In another aspect of the invention, the gels include two components. Thefirst component includes a water-soluble (co)polymer, which ispreferably from about 1 to about 50 weight % in a solution. Thewater-soluble (co)polymer of the first component is prepared by grafting(meth)acrolin onto a (co)polymer. The second component includes a watersoluble (co)polymer, which is preferably from about 1 to about 20 weight% in a solution. The water soluble (co)polymer of the second componentis functionalized with an amino group, alcohol, acid, or mixturesthereof.

In another embodiment, the (meth)acrolien can be grafted ontopoly(ethylene oxide), poly(propylene oxide), or homopolymers or(co)polymers of ethylene glycol or N-vinyl pyrrolidone. The watersoluble (co)polymer containing amide, alcohol or acid functionalityincludes poly(ethylene imine), poly(vinylalcohol), chitosan, cellulose,poly((meth)acrylic acid)), and (co)polymers thereof. The weight ratio ofthe first component to the second component can be from about 12:1 toabout 1:1.

The hydrophilic gel of the present invention can be formed by mixing anaqueous solution of a poly(aldehyde) or (co)polymer with an aqueoussolution of a poly (amine), poly(alcohol) or a poly(amide) in a weightratio from about 12:1 to about 1:1.

For example, an aqueous solution of poly(N-vinyl lactam) can be mixedwith a polymerizable aldehyde to form an aqueous solution of ahydrophilic poly(aldehyde). The aqueous solution of poly(N-vinyl lactam)contains from about 5% to about 50% poly(N-vinyl lactam). The resultingaqueous solution of hydrophilic poly(aldehyde) contains from about 5% byweight to about 50% by weight poly(aldehyde). The resultingpoly(aldehyde) is then mixed with an aqueous solution of poly(amine),poly(alcohol) or poly(amide) in a ratio from about 12:1 by weight toabout 1:1 by weight to produce a blend having a total polymer contentfrom about 1 weight percent to about 50 weight %, and preferably from 5%weight to 15 weight %, of poly(aldehyde), poly(amine), poly(amide) andpoly(alcohol).

The aqueous solution of poly(amine) contains from about 5% by weight toabout 50% by weight poly(amine). The aqueous solution of poly(amide)contains from about 5% by weight to about 50% by weight of poly(amide).The aqueous solution of poly(alcohol) contains from about 5% by weightto about 50% by weight poly(alcohol).

The resulting blend is allowed to cure for a time from about 10 secondsto about 2 hours until a hydrophilic, irreversible gel is formed. Thetime and temperature for curing are not critical. For purposes ofconvenience, ambient temperature may be used but the time can beshortened at elevated temperatures.

In another embodiment, the method for preparing a stable, irreverisablehydrophilic gel includes adding a biologically active material to themixture of aqueous solutions. The biologically active material can be ananti-microbial agent.

The hydrophilic gel can be formed into a dressing by casting twoseparate slabs of the gel onto two substrates, applying a solution of abiologically active material onto a surface of one of the slabs, andcompressing the slabs together with the biologically active materiallocated between the slabs.

The gel preferably includes at least one additional ingredient which maybe releasable from the gel. Preferably, the releasable ingredient is asurfactant, a fragrance, a biologically active material, or abioeffecting or body-treating material.

The term gel is intended to mean viscous or semi-solid and jelly-like.The gels of the present invention are stable and therefore irreversibleand water insoluble, even in boiling water or alcohol. The gels arehydrophilic and capable of absorbing many times their weight in water orat least 100% their weight in water. Herein the term “tacky” is intendedto mean having the property of being sticky to the touch or adhesive toa degree that the gel is capable of sticking to the skin while beingeasily removable when removal is desired.

While the exact nature of the mechanism by which the gel forms is notknown, and while it is not intended to be bound by theory, it isbelieved that the addition of poly(aldehyde) to a polymer compoundbearing amine, amide or alcohol functionalities gives rise to covalentcross-linking dispersed through an interconnecting network of ionicbonds present in the poly(amide), poly(amine) or poly(alcohol).

Many different types of additional materials may be incorporated intothe gels of the present invention including organic salts, inorganicsalts at low concentrations, alcohols, amines, polymer lattices,fillers, surfactants, pigments, dyes, fragrances and so forth as long asthey do not interfere with gel formation. Many of these materials can bereleased directly from the gel.

The gels of this invention are especially useful as carriers for a widevariety of releasable biologically-active substances having curative ortherapeutic value for human or non-human animals. Included among thebiologically-active materials which are suitable for incorporation intothe gels of the invention are hormones, hypnotics, sedatives,tranquilizers, anti-convulsants, muscle relaxants, analgesics,antipyretic agents, anti-inflammatory agents, local anesthetics,antispasmodics, antiulcer agents, antivirals, antibacterials,antifungals, sympathomimetic agents, cardiovascular agents, antitumoragents, and so forth. A biologically-active substance is added inpharmaceutically-active amounts.

Particularly preferred as biologically-active additives arenitroglycerine, scopolamine, pilocarpine, ergotamine tartrate,phenylpropanolamine, and theophylline; also antimicrobials such astetracycline, neomycin, oxytetracycline, triclosan, sodium cefazolin,silver sulfadiazine, and also salicylates such as methylsalicylate andsalicyclic acid, nicotinates such as methyl nicotinate; capsaicin,benzocaine, a-hydroxy acids, vitamins and biostats.

When the gel is to be used for cosmetic treatment, hydrating agents suchas sodium pyrrolidine carboxylic acid, polyols, and polymers may beadded. For a hydrating purpose, however, the large amount of water alonewhich can be absorbed by the hydrophilic gel serves a hydrating functionto the skin.

Water-soluble and water-insoluble additives such as those describedabove may be initially mixed with the aqueous solvent before the gelpreparation is begun, may be mixed with the aqueous solution ofpoly(N-vinyl lactam) or mixed with the aqueous solution of poly(amine),poly(amide) or poly(alcohol) during the gel preparation. Water-solubleingredients are preferably mixed in with the PVP prior to admixing withthe amine, amide or alcohol functionality bearing polymer. One can alsoemulsify water insolubles by adding surfactants to either thepoly(N-vinyl lactam) or poly(amine), poly(amide) or poly(alcohol).Alternatively, additives may be similarly mixed into the gel preparationafter the poly(N-vinyl lactam) is blended with the poly(amine),poly(amide), poly(alcohol). Additives may also be applied to the surfaceof a gel dressing, for example, by spraying, dipping, brushing orrolling.

The gel may be used to make adsorbent wound packing agents or dressings,skin masks or wraps, drug delivery patches, implants and dry filmproducts.

When the gel is used as a wound packing or cavity-filling wounddressing, it advantageously provides the desired properties of suchdressings, such as (1) biocompatability; (2) ability to conform to awound cavity; (3) non-adherence to the wound; (4) ability to absorbexudate; (5) ability to remove in one piece from the wound; (6) abilityto hold its physical integrity when swollen with exudate; (7) ease ofhandling because it is not too sticky.

When used as a skin-hydrating mask, the gel has excellent hydratingcapacity, advantageously contains no alcohol, and is easily and cleanlyremoved.

When used as an implant, the gel has excellent ability to maintain itsphysical integrity under different conditions, such as heat and aqueous.The gel is also biocompatible which makes it an excellent candidate asan implant.

When made into a dry film and used as a skin mask, it provides aflexible, clear, hydrophilic film which adheres to the skin when wettedwith water. The film can retain active moisturizers and otheringredients close to the skin, helping in their delivery. The film canalso be easily peeled off after a period of time without leavingresidues.

To obtain the products of the invention, the gel may be packaged byitself in a mold, in a dry film form, or as a two-part system whichrequires mixing prior to use; or may be provided on a substrate andcovered with a release liner to prevent the gel from sticking to itself.The release line is removed prior to application to skin.

The substrate may fulfill one or several functions including providingreinforcement, providing a gas and liquid barrier, providing a supportwith air permeability, providing protection for the gel and the area oftreatment, and the like. Substrate selection to provide the desiredproperties is known to those skilled in the art. Useful substratesinclude but are not limited to a polymer film, a collagen film, or wovenfabric, a non-woven fabric and mixtures thereof. Preferred substratesinclude a polyurethane or a polyester film, a stretchable material, arelease liner and mixtures thereof.

The gel may be coated or spread onto a backing or substrate by any meansknown in the art. The gel can be combined with or adhered to a virtuallyunlimited variety of substrates or backings including resins, metalfoils, woven and non-woven webs of natural and synthetic fibers, etc. Abacking which provides gas and liquid barrier properties may be apolymer film such as polyurethane. Desirable composites with the gel mayalso be made using films of polyester, polyvinyl alcohol, orpolyvinylidene chloride. When the gel has a barrier substrate, theresulting structure has particular utility as a wound and burn dressing.Moisture is kept in and excess exudate is absorbed to promote healingbut bacteria are prevented from entering the wound or burn area, andmicrobial stasis may be maintained through the incorporation of ananti-microbial agent into the gel to prevent infection. For ease of use,the tacky gel on a backing is covered with a release liner which may bea silicone-coated film or polyethylene.

The gel may be coated onto the backing so that the gel occupies all orpart of the backing surface. If the gel occupies part of the backingsurface, non-gel coated areas of the backing may be provided with anadditional adhesive. The gel can also contain tackifiers such aspolyacids, polyols, and polyamines which can boost tack. A dressing ofthis type is positioned on the skin so that the additional skin adhesivecomes into contact with intact skin while the absorbent gel contacts awound. The additional adhesive provides a dressing with staying powerwhen the absorbent gel has become substantially saturated with woundexudate thus losing some of its adhesiveness through a dilution effect.In a preferred embodiment the dressing is formed by casting two separateslabs of gel onto two separate substrates, applying a solution of abiologically-active material to a surface of one of the slabs andcompressing the slabs together so that the biologically-active materialis sandwiched between the two slabs.

In still another embodiment, the gel may be used in adermatologically-compatible composition for cosmetic preparations andcosmetic wrap dressings. In yet another embodiment, the gel may be usedin cosmetic preparations such as face masks and nail wraps. The gelserves a hydrating fiction with or without a backing and a cosmeticeffect may be enhanced with the incorporation of other ingredients. Akit for a cosmetic gel may comprise a ready-made gel or two components:a poly(N-vinyl lactam) component and alcohol, amine or amidefunctionality bearing polymer component. Other cosmetic agents such ashydrating agents, fragrances, and the like can also be supplied to theready-made gel or to either component. For use, the components may bemixed and applied. The gel advantageously can be easily peeled off afteruse. It shall be understood that the term cosmetic means a preparationintended to enhance or improve physical appearance.

In a further embodiment, fragrances may be incorporated into the gel.When the gel is kept moist in a suitable vented container, the fragranceis slowly released as an air freshener.

The following examples are intended to illustrate but not limit theinvention. In the following examples irreversible, hydrophilic gels areformed which do not leech aldehydes and can be used as a wound, burndressing, implants or for cosmetic applications.

EXAMPLE 1

To three separate 250 milliliter round-bottom flasks equipped with astirrer, reflux condenser and thermometer 99.0 grams of a 10% solutionof PVP (Kollidon 90F, BASF) was added to the first flask; (2) 99.0 gramsof a 10% solution of poly(ethylene glycol) was added to the secondflask; and 99.0 grams of a 10% solution of poly(ethylene diamine) wasadded to the third flask. The solution was heated to 60° C. withstirring, then 0.5 grams of a water soluble initiator (Wako V-50, DockResins Co.) was added to each flask and the solution of each flask wasstirred for thirty minutes. 0.5 grams of acrolien, a polymerizablealdehyde manufactured by Aldrich Chemical Co., was then added to eachflask and the resulting solution was heated to 75° C. for six hours withstirring. When mixed with polymers with alcohol, amide or aminefunctionalities, each of the PVP, poly(ethylene glycol), andpoly(ethylene diamine) in each flask forms a hydrophilic, irreversiblegel, with no leechable aldehydes detected.

EXAMPLE 2

To a 250 milliliter round-bottom flask equipped with a stirrer, refluxcondenser and thermometer 99.0 grams of a 25% solution of PEG (Carbowax,Fischer Co.) was added. The solution was heated to 60° C. with stirring,then 0.5 grams of a water soluble initiator (hydrogen peroxide, AldrichChemical Co.) was added, and the solution was stirred for thirtyminutes. 0.5 grams of a polymerizable aldehyde (acrolien, AldrichChemical Co.) was then added and the solution was heated to 75° C. forsix hours with stirring. When mixed with polymers with alcohol, amine,or amide functionalities, PEG forms a hydrophilic, irreversible gel,with no leechable aldehydes detected.

EXAMPLE 3

To a 250 milliliter round-bottom flask equipped with a stirrer, refluxcondenser and thermometer, was added 99.4 grams of a 10% solution of PVP(Kollidon 90F, BASF) was added. The solution was heated to 60° C. withstirring, then 0.5 grams of a water soluble initiator (sodiumpersulfate, Aldrich Chemical Co.) was added, and the solution wasstirred for thirty minutes. 0.1 grams of a polymerizable aldehyde(acrolien, Aldrich Chemical Co.) was then added and the solution washeated to 75° C. for six hours with stirring. When mixed with polymerswith alcohol, amide, or amine functionalities, PVP forms a hydrophilic,irreversible gel, with no leechable aldehydes detected.

EXAMPLE 4

To a 250 milliliter round-bottom flask equipped with a stirrer, refluxcondenser and thermometer, 20 grams vinyl pyrrolidone (Aldrich ChemicalCo.) and 79 grams water were added. The solution was heated to 60° C.with stirring, then 0.5 grams of a water soluble initiator (Wako V-50)was added, and the solution was stirred for ten minutes. 0.1 grams of aacrolien, a polymerizable aldehyde manufactured by Aldrich Chemical Co.,was then added and the resulting solution was heated to 75° C. for sixhours with stirring. When mixed with compounds with alcohol, amide, oramine functionalities, PVP forms a hydrophilic, irreversible gel, withno leechable aldehydes detected.

EXAMPLE 5

To a beaker containing 50 grams of a polymer, described in Example 1, 3grams of lactic acid were added with stirring. Once thoroughly mixed, 47grams of a 50% solution of Polymin, a poly(amine) manufactured by BASFwas added with stirring. The resulting gel was tacky, pliable,incorporated 1.5% lactic Acid, which can be used for cosmeticapplications.

EXAMPLE 6

To a beaker containing 50 grams of PVP described in Example 3 was added50 grams of a dilute chitosan solution was added with stirring. Theresulting gel was irreversible at 130° C. and was pliable and relativelynon-adherent to a wound. The gel, when put into excess water or salinesolution at room temperature, absorbed water but did not dissolve ordisintegrate over a period of several days. It was found that the gelabsorbed 1,020% of its weight in water or saline. The gel can be used asa wound or burn dressing because it was tacky, but non-adherent to thewound.

EXAMPLE 7

A portion of the gel formed in Example 5 was dried to form a thinflexible film, which was soaked in water at room temperature. The filmabsorbed 150% water expanding in the process.

Thus, while there have been described what are presently believed to bethe preferred embodiments, those skilled in the art will appreciate thatother and further changes and modifications can be made withoutdeparting from the true spirit of the invention, and it is intended toinclude all such changes and modifications within the scope of theclaims which are appended hereto.

What is claimed is:
 1. A stable, irreversible, hydrophilic gelcomprising: (a) a first component comprising a water-soluble (co)polymerprepared by grafting (meth)acrolein onto poly(ethylene oxide),poly(propylene oxide), or homopolymers or (co)polymers of ethyleneglycol or N-vinyl pyrrolidone; (b) a second component comprising afunctionalized water soluble (co)polymer, wherein said (co)polymer is apoly(amide), a poly(amine), a poly(alcohol), a poly(acid), (co)polymersthereof or mixtures thereof.
 2. The stable, irreversible, hydrophilicgel according to claim 1 wherein said first component comprises a 1 to50 wt % solution of said water-soluble (co)polymer.
 3. The stable,irreversible, hydrophilic gel according to claim 1 wherein said secondcomponent comprises a 1-20 wt % solution of said functionalizedwater-soluble copolymer.
 4. The hydrophilic gel of claim 1 wherein saidsecond component comprises poly(ethylene imine), poly(vinylalcohol),chitosan, cellulose, poly((meth)acrylic acid), or (co)polymers thereof.5. The hydrophilic gel of claim 4 wherein said gel is prepared in anaqueous solution at a total polymer concentration of from about 5 weightpercent to about 50 weight percent.
 6. The hydrophilic gel of claim 5wherein said aqueous solution comprises water or a mixture of water andalcohol.
 7. The hydrophilic gel of claim 1 wherein the weight ratio ofsaid first component to said second component is from about 12:1 toabout 1:1.
 8. The hydrophilic gel of claim 1 wherein said gel isprepared in an aqueous solution at a total polymer concentration of fromabout 5 weight percent to about 50 weight percent.
 9. The hydrophilicgel of claim 8 wherein said aqueous solution comprises water or amixture of water and alcohol.
 10. The hydrophilic gel of claim 1 whereinsaid (meth)acrolein is grafted onto homopolymers or (co)polymers ofN-vinylpyrrolidone.
 11. The hydrophilic gel of claim 1 wherein saidfunctionalized water soluble (co)polymer is poly(vinyl alcohol),poly((meth)acrylic acid) or (co)polymers thereof.
 12. A method forpreparing a stable, irreversible hydrophilic gel comprising: (a)preparing a first aqueous solution comprising a poly(aldehyde) bygrafting (meth)acrolein poly(ethylene oxide), poly(propylene oxide), orhomopolymers or (co)polymers of ethylene glycol or N-vinyl pyrrolidone;and (b) mixing said first aqueous solution with a second aqueoussolution comprising a poly (amine), a poly(alcohol), a poly(amide), apoly(acid), (co)polymers thereof or mixtures thereof in a weight ratiofrom about 12:1 to about 1:1 to form a resultant solution; (c) curingthe resultant solution until a gel is formed.
 13. The method claim 12wherein said curing is performed for a period of time of from about 10seconds to about 2 hours.
 14. The method of claim 12, wherein said gelis prepared in an aqueous solution at a total polymer concentration offrom about 5 weight percent to about 50 weight percent.
 15. The methodof claim 14, wherein said aqueous solution comprises water or a mixtureof water and alcohol.